Recent developments in the field of video signal processing have produced digital high definition television (HDTV) signal processing and transmission systems. An HDTV terrestrial broadcast system recently proposed as the Grand Alliance HDTV system in the United States employs a vestigial sideband (VSB) transmission format for transmitting a packetized datastream. The Grand Alliance HDTV system is a proposed transmission standard that is under consideration in the United States by the Federal Communications Commission (FCC) through its Advisory Committee of Advanced Television Service (ACATS). A description of the Grand Alliance HDTV system as submitted to the ACATS Technical Subgroup Feb. 22, 1994 (draft document) is found in the 1994 Proceedings of the National Association of Broadcasters, 48th Annual Broadcast Engineering Conference Proceedings, Mar. 20-24, 1994.
The Grand Alliance HDTV system supports image information in two raster line scanning formats. One format is a 2:1 line interlaced format with a 30 Hz frame rate. The other is a 1:1 non-interlaced, or progressive (line sequential) format with a 60 Hz frame rate. The interlaced image display exhibits the following characteristics:
2200 pixels.times.1125 image lines (total) PA1 1920 pixels.times.1080 image lines (active). PA1 1600 pixels.times.787.5 image lines (total) PA1 1280 pixels.times.720 image lines (active).
The progressive image display exhibits the following characteristics:
Source material to be transmitted to a television receiver may exhibit either format. For example, a broadcast television program from one source may be in progressive form while one or more commercials or other intervening material from other sources may be in interlaced form.